Update guest input and CAN configuration for QEMU+KVM demo

Update guest input and CAN configuration for QEMU+KVM demo

Changes:
- Tweak agl-qemu-runner to make CAN options configurable.
- Update the IVI guest image agl-qemu-runner configurations to
  enable an emulated PCI CAN device mapped to the host can0.
- Update the IVI guest image agl-qemu-runner configurations to
  change the input device to a USB passthrough corresponding to
  the bottom USB 2.0 connector of the 2x stack on the reference
  hardware, so that a USB touchscreen can be used for demos.

Bug-AGL: SPEC-4618

Change-Id: I6b690377f5fe0a481e283d7370cbb165478ee8eb
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
(cherry picked from commit 0eb0e7ad872bc03cbc8af5c95bfe0219ebf06bfd)